Interaction of a Ni(II) tetraazaannulene complex with elongated fullerenes as simple models for carbon nanotubes

Abstract

Nickel(II) complex of 5,14-dihydro-6,8,15,17-tetramethyldibenzo[b,i][1,4,8,11] tetraazacyclotetradecine (NiTMTAA), which can be employed for noncovalent functionalization of carbon nanotubes (CNTs), represents a more complex and interesting case in terms of structure of the resulting nanohybrids, as compared to the related materials functionalized with porphyrins and phthalocyanines. Due to its saddle shape, the NiTMTAA molecule adsorbed can adopt different, energetically non-equivalent orientations with respect to CNT, depending on whether CH3 or C6H4 groups contact the latter. The main goal of the present work was to provide information on the interactions of NiTMTAA with simple single-walled CNT (SWNT) models accessible for dispersion-corrected DFT calculations. For reasons of comparison, we employed three such functionals: M06-2X and LC-BLYP as implemented in Gaussian 09 package, and PBE-G as implemented in Materials Studio 6.0. In order to roughly estimate the effect of nanotube chirality on the interaction strenght, we considered two short closed-end SWNT models (also referred to as 'elongated fullerenes'), one armchair and one zigzag, derived from C60 and C80 hemispheres. In addition, we calculated similar complexes with C60, as well as I h and D 5h isomers of C80. The results were analyzed in terms of optimized geometries, formation energies, HOMO-LUMO gap energies, and intermolecular separations. Graphical Abstract Interaction of Ni(II) tetraazaannulene complex with elongated fullerenes.

Noncovalent interactions of free-base phthalocyanine with elongated fullerenes as carbon nanotube models

“…The corresponding energies are slightly higher for H 2 Pc+C 60 , namely, 0.90 eV as calculated with PBE+D and PBE+D CP vs. 3.26-3.29 eV obtained with Truhlar's functionals. This trend for PBE+D functional to produce too low HOMO-LUMO gap values as compared to those computed with other functionals was noticed previously [43].…”

“…3). The latter exhibits an orbital distribution which is common for noncovalent complexes of porphyrins, phthalocyanines and related macrocycles with C 60 fullerene [2-5, 9, 42], as well as was observed for NiTMTAA adsorbed on the same ANT nanotube model as employed in the present report [43]: while HOMO is mainly located on the macrocyclic molecule, LUMO is found entirely (or almost entirely) on fullerene. In contrast, in the complex with nanotube a distribution approaching this one was obtained in M05-2X calculations only (except for a minor HOMO fraction extended to ANT), whereas M06-2X without and with BSSE correction gave HOMO almost uniformly distributed between H 2 Pc and ANT, and according to PBE+D, both orbitals are located on the nanotube unit.…”

“…However, the cost of this advantage is a smaller size of nanotube model. The closed-cap SWNT models used here were derived from spherical fullerenes C 60 and C 80 (I h ) to form armchair (5,5) and zigzag (10,0) SWNTs, which are composed of 120 and 140 carbon atoms, and referred to as ANT and ZNT, respectively [43]. The length of both nanotube models is barely sufficient to accommodate H 2 Pc macrocycle, with an overwhelming part of the latter contacting the nanotube part with cylindrical curvature.…”

“…Three functionals implemented in two different program packages were employed: one pure dispersioncorrected GGA functional (PBE) and two hybrid meta exchange-correlation functionals (M05-2X and M06-2X), which gave the best results for noncovalent hybrids of similar tetraazamacrocyclic compounds with fullerenes and SWNT models [42,43]. In order to estimate the effect of SWNT chirality on the interaction strength, we considered two short SWNT models (which can be referred to as 'elongated fullerenes' or 'fulleroids'), one armchair and one zigzag, whose ends were capped with C 60 and C 80 (spherical with I h symmetry) fullerenes [43]. Accordingly, for comparison, we performed calculations on noncovalent H 2 Pc+fullerene complexes with C 60 and C 80 .…”

Graphene oxide and nanodiamond: same carboxylic groups, different complexation properties

“…This computational methodology was shown to be efficient for the description of noncovalent interactions between tetraazamacrocyclic compounds with different carbon nanoclusters (fullerenes, fulleroid nanotube models and oxidized graphene sheets). 29,[47][48][49] Full geometry optimization and calculation of electronic parameters was performed with the following settings: 'ne' quality and convergence criteria, all-electron core treatment, a global orbital cutoff of 4.5Å and Fermi orbital occupancy (no thermal smearing).…”